Multiband wireless power system

ABSTRACT

The present disclosure relates to a module for relaying power wirelessly to a device implanted in a user. The module may include a structure adapted to be worn by the user, a receiver configured to receive a first wireless power transmission at a first frequency, a transmitter configured to transmit a second wireless power transmission at a second frequency different from the first frequency, and a frequency changer configured to convert energy generated by the first wireless power transmission into energy for generating the second wireless power transmission. Each of the receiver, transmitter and frequency changer may be disposed on or in the structure.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation of U.S. patent application Ser. No.15/976,475 filed May 10, 2018 and is a Continuation of U.S. patentapplication Ser. No. 15/596,740, filed May 16, 2017, now Issued U.S.Pat. No. 9,991,734, issued Jun. 5, 2018 and is a Continuation of U.S.Utility patent application Ser. No. 14/461,612, filed Aug. 18, 2014,entitled MULTIBAND WIRELESS POWER SYSTEM, now Issued U.S. Pat. No.9,680,330, issued Jun. 13, 2017 and is related to and claims priority toU.S. Provisional Patent Application Ser. No. 61/867,406, filed Aug. 19,2013, entitled MULTIB AND WIRELESS POWER SYSTEM, the entirety of whichis incorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

n/a

TECHNICAL FIELD

The present invention relates to a transcutaneous energy transfer (TET)system, and more particularly to a device for transferring or relayingpower wirelessly within a TET system, as well methods of operating thesystem and/or device.

BACKGROUND

TET systems are used to supply power to devices such as pumps implantedinternally within the human body. An electromagnetic field generated bya transmitting coil outside the body can transmit power across acutaneous (skin) barrier to a magnetic receiving coil implanted withinthe body. The receiving coil can then transfer the received power to theimplanted pump or other internal device and to one or more batteriesimplanted within the body to charge the battery.

One of the challenges presented by TET systems is to provide sufficientpower to the internal device to enable continuous operation of theinternal device. For this purpose, the TET system may include animplanted battery that stores power for operating the internal device.However, the implanted battery's supply is limited and may need to berecharged frequently. The TET system may also, or alternatively, includean external TET power unit to supply the internal device's entire powerdemand. However, the external TET power unit also has a limited supplyand may need to be recharged regularly. Moreover, some activities suchas showering or swimming may preclude wearing the external TET powerunit.

Constant recharging of an external TET power unit, as well as animplanted battery is an inconvenience for a user with the internaldevice(s). Ordinarily, the external TET power unit must be plugged intoa charging station in order to be recharged. A user may have to wait forthe unit to sufficiently charge before wearing the unit. Alternatively,the user may replace the battery in the external TET power unit with afully charged battery.

It is therefore desirable to improve upon present TET systems to makerecharging of external TET power units and implanted batteries moreconvenient for the user.

SUMMARY

One aspect of the present disclosure provides for a module for relayingpower wirelessly to a device implanted in a user. The module may includea structure adapted to be worn by the user, a receiver configured toreceive a first wireless power transmission at a first frequency, atransmitter configured to transmit a second wireless power transmissionat a second frequency different from the first frequency, and afrequency changer electrically coupled to each of the transmitter andreceiver and configured to convert energy generated by the firstwireless power transmission into energy for generating the secondwireless power transmission. Each of the receiver, transmitter andfrequency changer may be disposed on or in the structure. In someexamples, the first frequency and second frequency may belong todifferent frequency bands. In other examples, the first frequency may bemore than twice as great as the second frequency. In further examples,the respective frequencies may be selected for different distances, andmay be selected for different media.

The module may further include a control circuit configured to determinea wireless power transmission efficiency of the receiver and todynamically adjust the first frequency based on said determination. Thecontrol circuit may determine wireless power transmission efficiencybased on a measured peak signal at the receiver. The module mayadditionally or alternatively include a battery electrically coupled tothe receiver and a control circuit for determining whether to storeenergy generated by the first wireless power transmission in thebattery, to relay the energy generated by the first wireless powertransmission to the transmitter, or both.

The structure of the module may include a housing, the receiver andtransmitter being disposed within the housing. The module may be adaptedto be worn by the user such that the receiver is disposed at an end ofthe housing facing away from the user and the transmitter is disposed atan end of the housing facing towards the user.

Another aspect of the disclosure provides for a transcutaneous energytransfer system for delivering power to a device implanted within auser, including a module such as the module described above, and furtherincluding a remote power source electromagnetically couplable to themodule and configured to wirelessly transmit the first wireless powertransmission to the module, as well as an implanted receiver adapted forimplantation within the user, inductively couplable to the module andelectrically coupleable to the implanted device, and configured toreceive the second wireless power transmission from the module. Suchsystem may also include an external battery electrically coupled to themodule, used to store energy received from the first wireless powertransmission and to provide the stored energy to the transmitter togenerate the second wireless power transmission. Such system may furtherinclude an implanted battery electrically coupled to the implantedreceiver, used to store energy received from the second wireless powertransmission and to provide the stored energy to the implanted device inorder to power the device. The implanted battery may store energy whenthe module is worn by the user, and may power the implanted medicaldevice when the external charging module is not worn by the user. Theexternal battery may store energy when the module is electromagneticallycoupled to the remote power source, and may provide stored energy to thetransmitter when the module is not electromagnetically coupled to theremote power source.

A further aspect of the disclosure provides for an apparatus forrelaying power wirelessly, having a plurality of receiver circuitsadapted to receive a wireless power at a respective resonant frequencyof the receiver circuit, a transmitter circuit adapted to transmitwireless power at a selected resonant frequency, and a plurality offrequency changers. Each frequency changer may be electrically coupledto an output of a respective receiver circuit and to an input of thetransmitter circuit, and configured to convert the frequency of thewireless power received at the respective receiver circuit to theselected frequency. In some examples, each receiver circuit may beadapted to receive wireless power at a different frequency. Theapparatus may be included in a wireless energy which may further includea plurality of remote transmitter circuits. Each remote transmittercircuit may be adapted to generate and transmit wireless power at theresonant frequency of a corresponding receiver circuit at the apparatus.

Yet a further aspect of the disclosure provides for a transcutaneousenergy transfer system having an implanted wireless power receiverelectrically couplable to an implanted medical device, a remote powersource generating power sufficient to operate the implanted medicaldevice, and one or more wireless power relay apparatuses configured torelay power from the remote power source en route to the implantedwireless power receiver. Each apparatus may further include a receiveradapted to receive an incoming wireless power transmission at a firstfrequency, a transmitter adapted to transmit an outgoing wireless powertransmission at a second frequency; and a frequency changer electricallycoupled to the transmitter and to the receiver, and configured toconvert energy generated by the incoming wireless power transmissioninto energy for generating the outgoing wireless transmission. Aplurality of apparatuses may be serially electromagnetically coupled toone another such that the wireless power transmitted by an upstreamapparatus is the wireless power received at a seriallyelectromagnetically coupled downstream apparatus. The implanted wirelesspower receiver may further be adapted to receive the wireless powergenerated by a farthest downstream wireless power relay apparatus.

In some examples of the system, the farthest downstream wireless powerrelay apparatus may include an external battery electrically coupled tothe receiver. The external battery may be used to temporarily storecharge (e.g., when the farthest downstream wireless power relayapparatus is electromagnetically coupled to a respective upstreamapparatus) and generate power for driving the transmitter at the secondfrequency using said stored charge (e.g., when the farthest downstreamwireless power relay apparatus is not electromagnetically coupled to arespective upstream apparatus). Similarly, an implanted battery may beelectrically coupled to the implanted wireless power receiver and to theimplanted medical device to temporarily store charge (e.g., when thefarthest downstream wireless power relay apparatus is operativelycoupled to the implanted wireless power receiver) and to generate powersufficient for operating the implanted medical device (e.g., when thefarthest downstream wireless power relay apparatus is not operativelycoupled to the implanted wireless power receiver, when the farthestdownstream wireless power relay apparatus does not on its own generatesufficient power for operating the implanted medical device, etc.).

Yet another aspect of the disclosure provides for a method of relayingpower wirelessly to a device implanted in a user, involving, providing astructure adapted to be worn by the user, receiving a first wirelesspower transmission at a first frequency at a receiver disposed on or inthe structure, transmitting a second wireless power transmission at asecond frequency different from the first frequency from a transmitterdisposed on or in the structure, and converting energy generated by thefirst wireless power transmission into energy for generating the secondwireless power transmission at a frequency changer electrically coupledto the receiver and the transmitter and disposed on or in the structure.In some examples of the method, the first wireless power transmissionmay be transmitted over a distance that is greater than the distancethat the second wireless power transmission is transmitted. Also, insome examples of the method, the first wireless power transmission maybe transmitted through a medium that is different than the mediumthrough which the second wireless power transmission is transmitted.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention, and theattendant advantages and features thereof, will be more readilyunderstood by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings wherein:

FIG. 1 is a block and schematic diagram illustrating components of amultiband TET system in accordance with an embodiment of the invention;

FIG. 2 is a block and schematic diagram further illustrating componentsof each an external and implanted module of the multiband TET system ofFIG. 1 in accordance with an embodiment of the invention;

FIG. 3 is a block and schematic diagram further illustrating componentsof a multiband TET relay system in accordance with a further embodimentof the invention; and

FIG. 4 is a block and schematic diagram further illustrating componentsof another multiband TET relay system in accordance with yet anotherembodiment of the invention.

DETAILED DESCRIPTION

FIGS. 1 and 2 schematically illustrate a multiband transcutaneous energytransfer (TET) system 100 used to supply power to an implantedtherapeutic electrical device 102 in an internal cavity within the body,i.e., below the skin of a user 104. The implanted electrical device 102can include a pump such as for use in pumping blood as a ventricularassist device (“VAD”), for example. The implanted electrical device 102can include controlling circuitry to control, for example, a pump.

As depicted in FIG. 1, the multiband TET system 100 includes an externalmodule 110 having a primary power coil circuit 114, associated circuitry(shown in greater detail in FIG. 2) and an antenna 111 for wirelesslyreceiving power from a remote power source 112 electromagneticallycoupled to the external module 110. The external module components areall disposed in or on a structure that is mountable to (e.g., wearableby) the user 104. For example, the structure may include a housing 115which is small enough to be carried by the user. The housing 115 mayoptionally be equipped with devices for affixing it to the user as, forexample, belt loops adapted to secure the housing to a belt worn by theuser, or straps for securing it to the user's body. Alternatively thehousing 115 may be secured to the user's body by external devices suchas a bandle, clothing, or an adhesive.

An internal module 120 implanted underneath the skin of the user 104 hasa secondary power coil circuit 124, associated circuitry disposed in oneor more housings 125 and an output cable for supplying power to theimplanted electrical device 102. Power is transferred from the primarycoil 114 to the secondary coil 124 by means of inductive electromagneticcoupling, i.e., via interaction of a magnetic field overlapping theprimary 114 and secondary 124 coils. The voltage across each coil can belarge, for example, peak-to-peak voltages of 100 V to 400 V are notuncommon. To reduce losses due to skin effect, the primary coil 114 canbe fabricated using Litz wire, in which the primary coil 114 is made upof relatively thin, insulated wires twisted or woven together.

In order to facilitate power transfer between the external and implantedmodules, the antenna 111 of the external module 110 may be disposed atan “outward” facing side of the external module (i.e., facing away fromthe user 104), whereas the primary coil 114 may be disposed at an“inward” facing side (i.e., facing towards the user 104).

The external module 110 is further electrically connected to an externalrechargeable battery 130 or charge accumulator. The battery 130 may beincluded in or on the structure or may be kept separate from thestructure. The external battery may serve as a backup power source tothe remote power source 112. For example, the battery 130 may supplypower to the primary coil 114 of the module in order to generatewireless power in case power transmission to the external module 110 isinterrupted or in case the power demand of the implanted device 102changes. When the backup external battery 130 is sufficiently charged,the user is free to move out of range of the remote power source 112.

The implanted module 120 is also connected to a rechargeable battery 128or charge accumulator for supplying power to the implanted electricaldevice 102. As with the external battery 130, and as described ingreater detail below, the implanted battery 128 may serve as a backup incase power transmission from the remote power source 112 to the externalmodule 110 is interrupted, in case power transmission between theexternal 110 and implanted 120 modules is interrupted, or in case ofchanges in power demands. With the implanted battery 128 as a backup,the external TET module 110 can be disconnected when the user bathes orperforms other activities.

In the example of FIG. 1, the optimal frequency for wireless powertransmission may differ between the first stage (i.e., from the remotepower source 112 to the external module 110) and the second stage (i.e.,from the external module 110 to the implanted module 120). One suchreason for the difference in optimal frequencies may be a difference inthe distance for each stage of wireless power transfer. For example,power transferred from the remote power source 112 may travel severalmeters (e.g., between about 1 and about 10 meters) to the externalmodule 110, whereas power transferred between the external 110 andimplanted 120 modules may travel on the order of millimeters (e.g.,between about 5 and about 200 millimeters). Another reason for thedifference in optimal frequencies may be a difference in medium for eachstage of wireless power transfer. For example, power transferred fromthe remote power source 112 may travel from one room of a building orother structure (e.g., through wood, concrete, drywall, rock, air, etc.,or any combination of the above) to the external module 110, whereaspower transferred between the external 110 and implanted 120 modules maytravel through only air and/or the patient's skin. To summarize, changesin either distance or medium may affect the optimal frequency at whichpower is transferred wirelessly.

In order to accommodate these changes, the antenna 111 may receivewireless energy at a selected first frequency f₁, whereas the primaryand secondary coils of the multiband TET system 100 may transfer andreceive, respectively, wireless energy at a selected second frequencyf₂. In some instances, the first and second frequencies may belong toseparate frequency bands. For purposes of this disclosure, the term“frequency band” may refer to a predefined range of frequencies, such asthose set forth by the American Radio Relay League (ARRL) or Instituteof Electrical and Electronics Engineers (IEEE). “Separate” frequencybands may refer to two non-overlapping predefined ranges of frequencies.In some examples, the lowest frequency of one of the separate bands maybe more than double the highest frequency of the other band.

Optimizing the strength of relayed wireless power may take severalfactors into account, including both the strength of the relayed power,as well as the safety of the user. For example, the first stage ofwireless power transfer in the example of the TET system of FIG. 1 maytravel a significant distance (e.g., on the order of several meters). Assuch, the frequency f₁ at the first stage may be selected to ensure thatthe power is not adversely affected by the distance traveled. Forfurther example, the final stage of wireless power transfer travelsthrough the user's skin and tissue. As such, the frequency f₂ at thefinal stage may be selected to ensure safe penetration of the surface ofthe user's skin, while avoiding risks to the user's health (internalorgans), and overheating or radiation for instance if the primary andsecondary coils are not properly aligned. Frequencies f₁ and f₂ may fallwithin the radio frequency (RF) spectrum, and may range on the order ofkilohertz (kHz) to megahertz (MHz) depending on the particular factors(e.g., distance, relative orientation of the transmitting and receivingelements, etc.) impacting the transmitted power. For instance, thefrequency f₁ at the first stage may be between about 10 kHz and about3000 MHz, whereas the frequency f₂ at the second stage may be betweenabout 10 kHz and about 500 kHz.

FIG. 2 is a functional block diagram illustrating electrical componentsof the multiband TET system 100 of FIG. 1. As illustrated therein, theremote power source 112 of the system 100 includes a power source 202and a wireless power transmitter 204 electrically coupled to the powersource 202 and remote antenna 113. The transmitter 204 and antenna 113form a tank circuit having one or more capacitive elements coupled tothe inductive element and series resistance of the antenna. Using thepower received from the power source 202, the wireless power transmitter204 drives the remote antenna 113, which includes, to resonate at theresonant frequency f₁ dictated by the tuned capacitive/inductiveproperties of the transmitter/antenna, such that wireless power istransmitted from the remote antenna 113 to the antenna 111 of externalmodule 110 at the first frequency f₁.

The external module 110 includes a wireless power receiver 212electrically coupled to the antenna 111 thereby forming a tank circuit(comparable to the tank circuit of the remote power source 112) that isadapted to generate power from the wireless energy transmitted by theremote power source 112 by means of electromagnetic coupling. The powergenerated by the wireless power receiver 212 is at the resonantfrequency f₁. In some examples, the first frequency f₁ may bedynamically adjusted in order to optimize efficiency of the wirelesspower transfer. Efficiency may be affected by several factors, such asthe relative distance and relative orientation between the antenna 111and remote antenna 113, as well as the medium or media between theantenna 111 and remote antenna 113. Determining the efficiency of thewireless energy transfer may be based on a peak signal measured at thereceiver 212 and may further be based on known characteristics of a loadat the receiver 212. Such measurements and known information may berelayed between the external module 110 and the remote power source 112,for example using RF telemetry signals.

The associated circuitry of the external module further includes amicrocontroller 214, a power amplifier/driver 216, and a frequencychanger 218. Power received from the wireless transmitter 201 atfrequency f₁ is processed at the frequency changer 218 and provided tothe implanted module 120 by the TET driver 216 as controlled bymicrocontroller 214. The frequency changer may utilize a frequencymultiplier, doubler or mixer to raise or lower the frequency of thepower generated at the external module 110 from f₁ and f₂. Frequenciesf₁ and f₂ may belong to different frequency bands.

The microcontroller 214 may also be configured to determine and controlthe source or sources of power from which the wireless power at theprimary coil 114 is generated. The primary coil 114 may be powered fromthe remote power source 112, the external battery 130, or both. Forexample, when the external module 110 is communicatively coupled to theremote power source 112, the microcontroller 214 may determine to usethe power received from the remote power source 112. Additionally, anyexcess power not used in driving the primary coil 114 may instead bestored at the external battery 130. When the remote power source 112 isnot coupled to the external module 110, or during periods of peak powerdemand, the microcontroller 214 may determine to use charge stored atthe external battery 130 to drive the primary coil 114. Themicrocontroller 214 may operate one or more switches to route electricalcurrent from the selected source of power. The microcontroller 214 mayfurther control the routing of wireless power from the remote powersource to either or both the primary coil 114 and the external battery130, thereby coordinating the charging of the battery 130 with thedriving of the primary coil 114. For example, commonly owned U.S. Pat.No. 8,608,635, the disclosure of which is hereby incorporated herein inits entirety, describes a method of operation of a TET system the flowof electrical power from the external module to the implanted module isprecisely metered according to the instantaneous power demand of theimplanted device so that power is not drawn from the implanted batteryduring normal operation of the implanted device.

The transmission frequency of the primary coil 114 may be preset to, orin some examples dynamically set to, a desired transmission frequency(frequency f₂ in the example of FIGS. 1 and 2) in order to optimizepower transmission to the secondary coil of the implanted module 120.The microcontroller 214 may be capable of controlling the frequencychanger 218 in order to dynamically adjust the frequency of the receivedenergy at the wireless power receiver 212 to the desired transmissionfrequency f₂. In those examples where the desired frequency f₂ isdynamically set and updated, power optimization between the primary andsecondary coils, like power optimization between the remote power sourceand external module, may be based on measured peak signal values andknown load characteristics at the downstream module (which in thepresent example is the implanted module 120) and may be communicatedupstream via RF telemetry so that the upstream module's controller (inthis case the microcontroller 214 of the external module 110) controlsthe wireless power transmission frequency.

The implanted module 120 includes a TET receiver 222 and amicrocontroller 224 electrically coupled to the receiver. The TETreceiver 222, along with the secondary coil 124 forms a tuned resonantcircuit set to the transmission frequency f₂. The secondary coil 124,like the primary coil 114, may be fabricated using Litz wire. The TETreceiver 222 further includes rectifier circuitry (not shown), such asactive switching or a diode bridge, for converting an alternatingcurrent (“AC”) voltage at the secondary coil into a direct current(“DC”) voltage. DC power output from the TET receiver 222 is supplied tothe microcontroller 224, the implanted battery 128 and an implantedelectrical device 102. The implanted electrical device 102 can includeone or more of a variety of devices such as a VAD blood pump. The powerdemands of the implanted electrical device 102 are such that theimplanted battery 128 can only power the device for a limited amount oftime (e.g., a few hours, a day, etc.). In such case, the implantedbattery 128 does not serve as a main power source for the implanteddevice, but rather as a backup power source used to supply power forrelatively short periods of time in case of an interruption in thetransmission of power to the implanted module 120. For example, theimplanted module 120 can rely on battery power when the user takes offthe external module 110, such as in order to take a shower.

In each of the above examples, the wireless power received at thesecondary coil 124 of the implanted module could be used immediately topower the implanted device, temporarily stored at the implanted battery128 for future use, or both. Thus, some or all of the power can berouted to the implanted device 102, whereas remaining power can berouted to the implanted battery 128. The implanted microcontroller 224may be configured to determine whether to use or store the receivedwireless power. For instance, the controller may determine to storereceived power when the external module 110 is worn by the user 104, andto power the implanted medical device 102 using the stored charge whenthe external module 110 is removed from the user 104. Determiningwhether the external module 110 is being worn or removed from the user104 may be determined based on whether any electrical current is presentat the secondary coil.

In other examples, control over storing and/or use of wireless power maybe dictated by changes in power demands from the implanted device. Forinstance, if the implanted device requires an additional burst of power,the controller (either external 214 or implanted 224) may determine toprovide the extra power using stored charge (either in the external orimplanted battery). Such methods of control are described in detail incommonly owned U.S. Pat. No. 8,608,635. For further instance, if atemperature sensor indicates that an implanted or external electroniccomponent is operating inefficiently (overloaded, overheated, notaligned), the controller may determine to cease wireless powertransmission at least temporarily and continue operating the implantedmedical device 102 using energy from the implanted battery 128. Suchdeterminations may be made regardless of electrical, communicative, orinductive coupling between components of the TET system.

The external module 110 may include additional components not shown inFIG. 2, including, although not limited to, a thermal sensor, anover-voltage protection (OVP) circuit, and an RF telemetry system. Thesecomponents and their operation are described in greater detail incommonly owned U.S. Pat. No. 8,608,635.

The multiband TET system illustrated in FIGS. 1 and 2 includes only twostages: a first stage from the remote power source 112 to the externalmodule 110; and a second stage from the external module 110 to theimplanted module 120. Other multiband TET systems may include additionalstages for transferring/relaying power wirelessly. The additional stagesmay be in configured in series or in parallel with one another, or mayinclude any combination of serial/parallel connections.

The example multiband TET system 300 of FIG. 3 illustrates a seriallyconnected system including several wireless charging relay stations 310₁-310 _(n) as wireless repeaters to relay power wirelessly from a remotepower source 305 to an external module 330. The relay stations 310 ₁-310_(n) communicate with one another serially in an upstream-to-downstreamorder. Thus, the first relay station 310 ₁ passes power wirelessly tothe next downstream station 310 ₂ and so on to the farthest downstreamstation 310 _(n) Each relay station 310 ₁-310 _(n) includes a receiverantenna 320 ₁-320 _(n) and transmitter antenna 325 ₁-325 _(n) forrelaying the wireless power, as well as a frequency changer 315 ₁-315_(n) for converting the frequency of the received power to a newfrequency for the subsequent stage of transmission. The frequency ofeach relay stage may be fixed or preset based on known characteristicsof the system & environment (e.g., approximate distances and/or mediabetween each relay station). Alternatively, each relay station mayinclude a respective control circuit (not shown) for dynamicallycontrolling the frequency and/or frequency band of each relayed stagebased on certain factors, such as the distance, medium and/or relativeorientation between each respective transmitter/receiver pair. Whetherthe frequency changer 315 ₁-315 _(n) of a given station is instructed bythe control circuit to change the frequency of a given stage, and towhat frequency that stage is changed, may depend on those factors. Insuch an example, a downstream relay station may send telemetry signalsrepresentative of the power received, and the upstream relay station mayreceive these signals and adjust the transmission parameters in order tomaximize power received by the downstream relay station.

Operation of the serial multiband TET 300 begins with external remotepower source 305 generating and transmitting power wirelessly to thefirst wireless charging relay station 310 ₁ at a first frequency f₁. Thefirst wireless charging relay station 310 ₁ receives the power, thenconverts it to a second frequency f₂, and then transmits the convertedpower at the second frequency f₂ to the second wireless charging relaystation 310 ₂. As with the first station, the second station, and eachof the subsequent stations in turn, receives the power, converts it to adifferent frequency, and transmits it on to the next downstream stationuntil it is received at the external module 330 (at frequency f_(n-1))and relayed to the implanted module 340 via primary and secondary coils335/336 (at frequency f_(n)). Use of serially connected stations therebyincreases the overall distance over which power may be transmittedwirelessly.

As in the example embodiment of FIGS. 1 and 2, the second frequency f₂may be different than the first frequency f₁. Likewise, each powertransfer stage may be set to a different frequency. Alternatively, insome instances, the frequencies of some or all of the power transferstages may be the same, with each relay station increasing the overalldistance of wireless power transmission for the TET system.

The example multiband TET system of FIG. 4 illustrates a systemconnected in parallel including several wireless charging relay stations410 ₁-410 _(n). As with the example of FIG. 3, each station 410 _(1-n)includes each of a receiver antenna 420 ₁-420 _(n), a transmitterantenna 425 ₁-425 _(n), a frequency changer 415 ₁-415 _(n), and acontrol circuit (not shown) with capabilities similar to the analogouscomponents described in connection with FIG. 3.

Operation of the parallel multiband TET 400 begins with an externalpower source 405 generating and transmitting power wirelessly to each ofthe wireless charging relay stations 410 ₁-410 _(n) at a first frequencyf₁. Each wireless charging relay station 410 ₁-410 _(n) receives powertransmitted at frequency f₁, then converts it to a second frequency f₂,and then transmits it at the second frequency f₂ to the external module430, which then relays it to the implanted module 440 at the thirdfrequency f₃ via primary and secondary coils 435/436. As with theexample of FIG. 3, the first and second frequencies may be the same ordifferent. Power at each receiver of the external module may be combinedin the external receiver to provide more power to the implanted module.Use of charging stations connected in parallel thereby increases theamount of power that can be transmitted to the external module withoutincreasing the amount of power handled by any of the relay stations.

In another example of parallel relay of wireless power, the externalmodule may include a separate frequency changer for each relay stationcoupled thereto. In such an example, the external module may be capableof receiving wireless power at multiple frequencies, such as if eachrelay station is set to a different resonant frequency. For example,each relay station may be a different distance from the external module,or separated by a different medium, or both. In such a case, eachreceiver of the external module would be electrically coupled to theinput of a respective frequency changer, and each frequency changerwould change the frequency of the respective received wireless power toa common frequency before combining all of the received power. In orderto combine the wireless power received at each receiver, the externalmodule may be configured to convert all received power to a common ACfrequency, or to convert all received power to DC and using theconverted DC power to drive the primary coil of the external module.

In further examples of parallel relay of wireless power, each relaystation may receive power from a separate power source. This in turnpermits for improved charging while using smaller power sources in thecharging process.

In yet further examples of parallel relay of wireless power, one or moreexternal power sources may be configured to generate power at differentresonant frequencies (for example, at least two different frequencies).The power may then be relayed to different parallel relay stationshaving receivers tuned to the respective different frequencies. Alongthe same line, the external module may be equipped with multiplereceivers, so as to receive relayed power from each of the variousparallel relay stations. In such a situation, the external module mayinclude multiple frequency changers, each coupled to a respectivereceiver, as described above.

In yet further examples of parallel relay, instead of including multiplereceivers in the external module, the implanted module itself may beequipped with the multiple receivers. In such examples, the implantedmodule may further be equipped with circuitry to combine power receivedfrom multiple sources inside the user. In those examples, converting thepower to a common AC frequency would not be necessary, since all of thepower generated at the implanted receiver would be rectified to a DCvoltage for storage in the implanted battery and/or operating theimplanted medical device.

In some examples, parallel and serial systems may be used in combinationwith one another. The relay stations rely on intelligent switchingand/or adapting techniques known in the art in order to efficientlytransfer power from the power source to the external module, even if theexternal module is constantly moving from location to location, such asif the user were to walk from one end of a room or building to theopposite end while wearing the external module. Such techniques wouldinclude changes in the frequency of a transferred signal betweenstations, or changes in which station(s) the signal is relayed toefficiently transmit it to the external module. Altogether, the abovetechniques would allow the user to charge or recharge the externalmodule without having to remove the unit or to remain stationary. Simplyput, the present disclosure is not limited in the manner by which relaystations are arranged or organized or by the particular frequency (orfrequency band) received and/or transmitted at any given station.

While the above disclosure describes a TET system having discretemodules, each module containing all associated circuitry within aunitary structure (i.e., a housing), it will be recognized that thedisclosure is similarly applicable to any apparatus for wireless powerrelay, even without such a unitary structure. For instance, the externalmodule of FIGS. 1 and 2 may be adapted to include primary coils, powerreceiving circuitry, frequency changers, external batteries, etc.,contained in or mounted to different structures (e.g., a primary coilworn on the patient's chest and an external battery secured to thepatient's belt, etc.). The same is true of the implanted module. Forinstance, each of the secondary coil, the implanted microcontroller,rectifier, and implanted battery may be housed together or separately inany desired combination.

Furthermore, while the above disclosure generally describes a TET systemfor use in a user having an implanted VAD, it will be recognized thatthe disclosure is similarly applicable to any system having each of anon-transcutaneous and a transcutaneous stage of wireless powerdelivery. As such, the disclosure is similarly applicable for drivingany implanted device, and also applicable for driving a device implantedin any human patient or other animal.

Yet further, while the above disclosure primarily addresses advancementsin transcutaneous wireless power transfer systems, it will be recognizedthat the present disclosure may has broader application and benefits inother wireless power transfer systems. For instance, application of thepresent disclosure may be beneficial within any system having multiplestages of wireless power transfer of substantially varying lengths(e.g., meters as compared to centimeters, miles as compared to yards,etc.).

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

What is claimed is:
 1. A module for relaying power wirelessly to animplanted device, comprising: an external module; a receiver configuredto receive a first wireless power transmission at a first frequency; atransmitter configured to transmit a second wireless power transmissionat a second frequency different from the first frequency; a frequencychanger coupled to at least one from the group consisting of thetransmitter and the receiver, the frequency changer configured toconvert energy generated by the first wireless power transmission intoenergy for generating the second wireless power transmission; and atleast one from the group consisting of the receiver, transmitter, andfrequency changer are disposed at least one from the group consisting ofon the external module and in the external module.
 2. The module ofclaim 1, wherein each of the first frequency and second frequency belongto different frequency bands.
 3. The module of claim 1, wherein thefirst frequency is selected for wireless power transmission at a firstdistance and the second frequency is selected for wireless powertransmission at a second distance shorter than the first distance. 4.The module of claim 1, wherein the first frequency is selected forwireless power transmission through a first medium and the secondfrequency is selected for wireless power transmission through a secondmedium different than the first medium.
 5. The module of claim 1,further comprising a control circuit configured to determine a wirelesspower transmission efficiency of the receiver and to dynamically adjustthe first frequency based on said determination.
 6. The module of claim5, wherein the control circuit is configured to determine wireless powertransmission efficiency based on a measured peak signal at the receiver.7. The module of claim 1, wherein the first frequency is more than twiceas great as the second frequency.
 8. The module of claim 1, furthercomprising a battery electrically coupled to the receiver and a controlcircuit for determining whether to store energy generated by the firstwireless power transmission in the battery, to relay the energygenerated by the first wireless power transmission to the transmitter,or both.
 9. A transcutaneous energy transfer system, comprising: animplanted wireless power receiver; a remote power source; and a wirelesspower relay apparatus configured to relay power from the remote powersource to the implanted wireless power receiver, the apparatuscomprising: a receiver configured to receive an incoming wireless powertransmission at a first frequency; a transmitter configured to transmitan outgoing wireless power transmission at a second frequency; and afrequency changer in communication with at least one from the groupconsisting of the transmitter and the receiver, the frequency changerbeing configured to convert energy generated by the incoming wirelesspower transmission into energy for generating the outgoing wirelesstransmission.
 10. The system of claim 9, wherein the wireless powerrelay apparatus includes a plurality of apparatuses electromagneticallycoupled to one another, wherein the wireless power transmitted by anupstream apparatus of the plurality of apparatuses is the wireless powerreceived at a downstream one of the plurality of apparatuses, andwherein the implanted wireless power receiver is configured to receivethe wireless power generated by a farthest downstream wireless powerrelay apparatus of the plurality of apparatuses.
 11. The system of claim10, wherein the farthest downstream wireless power relay apparatus ofthe plurality of apparatuses further comprises an external batteryelectrically coupled to the receiver, the external battery being usedto: temporarily store charge when the farthest downstream wireless powerrelay apparatus of the plurality of apparatuses is electromagneticallycoupled to a respective upstream apparatus of the plurality ofapparatuses; and generate power for driving the transmitter at thesecond frequency using the stored charge when the farthest downstreamwireless power relay apparatus of the plurality of apparatuses is notelectromagnetically coupled to a respective upstream apparatus of theplurality of apparatuses.
 12. The system of claim 10, further comprisingan implanted battery electrically coupled to the implanted wirelesspower receiver, the implanted battery used to: temporarily store chargewhen the farthest downstream wireless power relay apparatus of theplurality of apparatuses is operatively coupled to the implantedwireless power receiver; and generate power when at least one from thegroup consisting of the farthest downstream wireless power relayapparatus of the plurality of apparatuses is not operatively coupled tothe implanted wireless power receiver and when the farthest downstreamwireless power relay apparatus of the plurality of apparatuses does noton its own generate power.